#[allow(unused_must_use)]
pub fn box_test() {
    use std::mem;

    #[allow(dead_code)]
    #[derive(Debug, Clone, Copy)]
    struct Point {
        x: f64,
        y: f64,
    }

    // A Rectangle can be specified by where its top left and bottom right
// corners are in space
    #[allow(dead_code)]
    struct Rectangle {
        top_left: Point,
        bottom_right: Point,
    }

    fn origin() -> Point {
        Point { x: 0.0, y: 0.0 }
    }

    fn boxed_origin() -> Box<Point> {
        // Allocate this point on the heap, and return a pointer to it
        Box::new(Point { x: 0.0, y: 0.0 })
    }

    // (all the type annotations are superfluous)
    // Stack allocated variables
    let point: Point = origin();
    let rectangle: Rectangle = Rectangle {
        top_left: origin(),
        bottom_right: Point { x: 3.0, y: -4.0 },
    };

    // Heap allocated rectangle
    let boxed_rectangle: Box<Rectangle> = Box::new(Rectangle {
        top_left: origin(),
        bottom_right: Point { x: 3.0, y: -4.0 },
    });

    // The output of functions can be boxed
    let boxed_point: Box<Point> = Box::new(origin());

    // Double indirection
    let box_in_a_box: Box<Box<Point>> = Box::new(boxed_origin());

    println!("Point occupies {} bytes on the stack",
             mem::size_of_val(&point));
    println!("Rectangle occupies {} bytes on the stack",
             mem::size_of_val(&rectangle));

    // box size == pointer size
    println!("Boxed point occupies {} bytes on the stack",
             mem::size_of_val(&boxed_point));
    println!("Boxed rectangle occupies {} bytes on the stack",
             mem::size_of_val(&boxed_rectangle));
    println!("Boxed box occupies {} bytes on the stack",
             mem::size_of_val(&box_in_a_box));

    // Copy the data contained in `boxed_point` into `unboxed_point`
    let unboxed_point: Point = *boxed_point;
    println!("Unboxed point occupies {} bytes on the stack",
             mem::size_of_val(&unboxed_point));

    String::from("");
}
